Tubulous boiler with radiant furnace



June 21, 1960 N. HO$TRUPPEDERSEN 2,941,516

TUBULOUS BOILER WITH RADIANT FURNACE 3 Sheets-Sheet 1 Filed NOV. 19, 1956 INVENTOR Niel 5 //os'rrup- Pea arse MM, 3W ATTORNEY 5 Filed Nov. 19, 1956 June 21, 1960 N. HOSTRUP-PEDERSEN 2,941,516

TUBULOUS BOILER WITH RADIANT FURNACE 3 Sheets-Sheet 5 2,941,516 rosu oos aonnn wrrn RADIANT FURNACE Niels Hostrup-Pedersen, Hellerup, Denmark, assignor to Aktieselskabet Burmeister & Wains Maski1i-0g Skibsbyggeri, Copenhagen, Denmark Filed Nov. 19, 1956, Ser. No, 623,186 Claims priority, application Denmark Nov. 18, 1955 7 Claims. (Cl. l22=23 5) The present invention relates to tubulous boilers of the type having a radiant furnace bounded by two side walls, two end walls, and an upper wall or vapourising tubes in which an upward flow of the generated mixture of water and steam occurs during the operation due to the hatural circulation. i

Such vapourising tubes are in the following for the sake of brevity called risers, and in the walls of the radiant furnace they may be mounted in a single layer either close together or suitably spaced, or two or more staga gered layers. v i v More precisely defined, the invention relates to a tubulous boiler, the radiant furnace of which has side walls composed of risers, a front Wall of risers continuing into an upper Wall of tubes terminating a waterarid steam-drum located in the rear part of the boiler and extending transversely and substantially for the full width thereof, and a riser rear-wall connected directly or rectly to the same drum.

It has been decided, here and in the following, to call the end of the boiler, where the Waterand steam-drum is located, the rear part, and thereby the wall of the radiant furnace which is nearest the and lies parallel to the latter becomes the rear Wall of the furnace and the opposite wall its front Wall, While the two remaining walls become the side walls. This terminology does not necessarily relate to the location of the fireplace in relation to the boiler or to the location of the firing means; the fire,- fi the P ac here the e e a hl alQl l 's UY stay during t e r 1, ?Y ll a r fr m th following, in different embodiments of the invention be located outside what is here called the front wall of the furnace as well as outside any one of its side Walls or at the opposite end of the boiler, and the firing may, dependent on the concrete design, be performed through any one of the walls of the radiant furnace or through its bottom or top.

The invention is characterized that the downcomer means for water to the lower ends of the risers in a manner known per se consist substantially or solely of a vertical wall of downcomer tubes mounted under the drum and extending wholly or substantially for the full length of the latter, the said downcomer tubes terminabing in a lower header and forming, together with the riser rear-Wall of the radiant furnace, one or more con.- vecticn passes with a boiler heating surface consisting of water tubes joined directly to the tubes of the vertieal above mentioned downcomer tube wall.

Thus, a compact and cheap construction of the total boiler with a convenient arrangement of the necessary radiation and convection heating surfaces is made possible, and a well-defined circulation is obtained in all parts of the boiler with downcomer tubes evenly distributed over the full width of the latter in contradistinction to what is the case in different other constructions, where it is attempted to achieve a simple, strong, and compact construction by the use of a cage-like design of the tube system with a fe ph isu ly W de athe downt wn '2 t le hrh sh hich Water and Stea if n ar le t an rom he apo i tubes, res ti e y B the construction according to the invention has been achieved that downcomer tubes are located only in the coolest part of the boiler, and that the complete tube system'can be built up of plane tube harps which can be assembled by comparatively few and easily performed assemblage weldings and which are excellently suited for a rational serial production.

in an expedient embodiment of the invention, the convection heating surface consists wholly or substantially of inclined tubes leading from the downcomer tubes, and hereby is achieved that an effective cross flow of the cornbustion gases and the vapourising tubes in the convection pass is obtained in the simplest possible Way. The clined tubes of the convection heating surface may achc dlna t th i t on ermina e n rise s the a er may be risers incorporated in bounding surfaces for the hdi n fur ace o m y Wholly or p tl b ci l risers mounted for such purpose. In both cases is achieved that the inclined-tube heating surface is provided completely without the use of the otherwise usual vertical headers, he in l ned be bei welded di t to th dhwhwmer ub s h hesaldr r r V n hea he sa sd e t emb men o t e invention there is, approximately in the middle of the convection pam, provided a riser wall which is mounted substantially such co vertically, parallel to the rear wall of the radiant furnace and to the downcomer tube wall, and divides the conveclo Pa s n o a nward Pa s a d an u d P s series'wonnected thereto, and hereby a suitably high velocity of thecombustion gases when sweeping the convection heating surface is obtained. I

The convection heating surface may also according to the invention be made up of plane tube harps, eachconsisting. of substantially vertical tubes connected below to a supply tube leading from a downcomer tube and above to an upper-Wall tube or a manifold. This design may due to the somewhat larger tube lengths give fewer welds per Square metre of the heating surface, and due to the, substantially longitudinal flow of the combustion gases along the tubes it permits a closer mounting of the latter than was the case with cross-flow.

The design according tothe invention permits a very convenient mounting of a superheater, if any, viz. in the combustion gas pass immediately after the radiant fur? nace, before the convection heating surface proper, but suitably screened from the furnace by the riser rear-wall of the latter. In this manner the superheater can be in: corporated in the .COnst lQIl H without entailing any in-. crease in the space requirements of the latter and under nditions that its vsize and the transmission of heat can easily be adapted to the requirements of the particular p ant vention is the fact that'large parts of the tube system of the boiler can be manufactured in the form of plane tube harps, this entailing thepossibility of an extensive stand.- ardization, so that boilers of the same type can be constructed for different outputs by the number of such components being varied, In particular may, according to the invention, each downcomer tube with its associated nks at shhv cl hll ho an h r s s conn c e t e latter form a plane tube harp, which preferably is separately produced, the production being carried out under application of rational production methods and as plain factory work, the plane elements being comparatively easy to transport and assemble at the place of use.

In case that the risers in the side walls of the radiant furnace and possibly also the risers in its front wall lead from lower headers, the lower header for the downcomer tube wall may conveniently according to the invention As mentioned above, an important feature of the in-.

be directly united with such lower side tube headers, so that together with the latter and preferably also together with a lower front wall header it forms a bed frame on which the tube system of the boiler is built up. This gives a particularly convenient and strong construction of the tube system which is itself capable of carrying the necessary refractory and insulating covering and which is not subjected to unfortunate heat stresses.

The invention also comprises embodiments modified with a view to the heating of Water or some other liquid Without any real development of steam in the boiler being intended. Such modifications will substantially differ from embodiments for the production of steam in that a capacious upper drum for separating water and steam is not required and will therefore be substituted by an ordinary manifold or header from which the delivery pipe for the hot liquid leads, whereas the supply conduit for liquid (the feed conduit) instead of being led into the upper drum, as is normal in steam-developing boilers is connected at a'suitable point in the lower part of the boiler. The boiler design proper and its advantages as regards manufacture and operation are not affected by these modifications which thermo-technically only entail that the water now flows through all the boiler tubes in the upward direction.

The invention will be further described in the following with reference to the accompanying drawing on which Fig. 1 diagrammatically shows a longitudinal section through part of an embodiment of a tubulous boiler aci cording to the invention, while Figs. 2-6, likewise diagrammatically, but on a smaller scale, illustrate modified embodiments.

In the drawing, 1 designates a radiant furnace bounded by two side walls, one of which is visible in all the figures, a front wall 2 continuing above into an upper wall 3, the tubes of which terminate direct in a waterand steam-drum 4 located transversely at the rear part of the boiler and extending the full width of the latter. The rear wall 5 of the radiant furnace consists of risers which along their vertical part are provided with welded-on fins closing the clearances between the tubes in the row. In the embodiment shown in Fig. 1, the tubes of the rear wall 5 are bent backwards alternately at different levels, as illustrated, so that between the sections of these tubes leading to the drum 4 the combustion gases are permitted to pass from the radiant furnace to a successive convection pass 17.

The drum 4 is supported by a vertical wall of vertical downcomer tubes 6, to which cover plates 13 are clamped, so that the downcomer tube wall forms the rear wall in an upwards-directed convection pass 18, from the upper end of which the combustion gases flow between the upper ends, offset alternately to opposite sides, of the downcomer tubes 6. Below, the downcomer tubes are welded to a transverse header 7 which extends the full width of the boiler and at its ends is connected to lower headers, not shown, for the risers of the sidewalls, the said headers being in turn connected with a lower header 8 for the risers 2 of the front wall. In the embodiment illustrated in Fig. 1, the front wall header has an offset forming a frame around a firing opening 9, in which for example an oil burner may be mounted through an aperture 10 in an air supply box 11.

From the lower part of each of the downcomer tubes 6 project a number of inclined tubes 14, which form a convection heating surface andterminate in the risers of the rear wall 5, while from the upper part of each downcomer tube there project a number of inclined tubes 15 which likewise form a convection heating surface and terminate in risers 16 leading from the middle of the downcomer tube and terminating in the drum 4. The risers 16 are covered with cover plates which are carried some distance down into the tube bank 14 and thus form a partition which divides the convection section into the downward pass 17 and the upward pass 18 connected thereto.

In the upper part ofthe convection pass 17 before the convection heating surface 14 proper a super-heater is provided, and down-stream of the convection pass 18 there is provided, in a known manner, in the flow path of the combustion gases an econorniser 20 or some other heat exchange surface for. utilizing the residual heat in the combustion gases.

It will be seen that each downcomer tube 6 with the inclined tubes leading therefrom and the risers connected with the latter forms a plane tube harp. These harps may be uniform throughout the width of the boiler, but are, however, conveniently of two different designs, viz. with the inclined tubes staggered half a tube pitch in relation to each other with a view to a better flow passage for the combustion gases through the banks of inclined tubes. The side-wall tubes or some of the latter may, instead of issuing from a lower header, issue direct from the outermost downcomer tubes, and the frontwall tubes 'or some of these tubes may likewise, instead of having a lower header 8, issue from the header 7 of the downcomer tube wall and extend forward, under or over the floor of the fire place to the front wall. The vertical sections of the front-wall tubes 2 may, as shown, be continued into the inclined upper-wall tubes 3, or a header may be provided here, or the front-wall tube and the upper-wall tube may be welded together at an angle.

The headers are in the usual manner provided with inspection covers, not shown, at the ends, through which covers examination and cleaning of sediment and incrustation can be performed, and besides, cleaning covers may be provided at the rear of the downcomer tubes in line with each inclined tube and where it might otherwise be considered necessary. Such cleaning covers are, however, preferably only used extensively in the case that the plant is to work under very poor feed-water conditions, as due to its simple design and well-defined circulation the boiler is well suited for the modern cleaning methods, by which incrustation, sediment, and other impurities are loosened and removed by treatment with inhibited acid, the so-called pickling.

The design permits, without any essential modifiications, an optional mounting of the firing means. Thus, one or more oil-burners, additional to or instead of the oil-burner in the front wall, may be inserted through the side wall by a suitable offset of the risers in a similar way as indicated by way of example in-the convection pass 17, where the free space thus obtained is intended to be used for an inspection or access cover or for the mounting of a soot blower.

It is, however, also possible to perform the firing through or below the downcomer tube wall, or the boiler construction shown in Fig. 1 may be raised bodily so much that an automatic firing apparatus can be inserted under the boiler.

A few characteristic examples of modified embodiments of the main principle of the invention are illustrated in Figs. 2--5.

Thus, Fig. 2 shows an embodiment which generally corresponds to Fig. 1. Here side headers 21 are shown which together with the downcomer tube header 7 and the front-wall header 8 form a closed bed frame for the total boiler construction. The principal difference from the embodiment in Fig. 1 consists in that the risers of the rear wall 5 of the radiant furnace and the risers of the dividing wall 16 in the convection pass are carried straight upwards and connected with the upper-wall tube directed convection pass with discharge of combustion gases to an economiser or air-preheater below.

Fig. 4 relates to the inverted arrangement mentioned above, where the firing is effected through an opening 9 in the downcomer tube Wall 6. It will be natural in such a case to have the fireplace located at the same end of the boiler. Finally, Fig. 5 shows an embodiment where the convection heating surface consists of substantially longitudinally-swept tube banks 23 composed of plane tube harps, the vertical tubes of which terminate in an upper manifold or header 24 which is here shown terminating in the associated riser 5. There is, however, nothing to prevent such a manifold or header for the whole of or part of such a tube harp from terminating direct in the drum 4. A partition 22 between the downward and the upward convection pass is here shown as a plate wall, but may just as well consist of vapourising tubes with welded-on fins.

Fig. 6 illustrates the above-mentioned modification, in which the boiler is particularly arranged for the heating of a liquid without any development of steam. The upper drum is substituted by a single manifold 34, and the feedwater is sent through a connection, not shown, into the lower bed frame composed of the headers 7, 8, 21 and 27, in which bed frame it is distributed to the upwardsextending boiler tubes. Thus, the vertical tube wall 26 directly under the manifold or header 34 in this modification functions as a riser wall, but the simple design of the tube system as a whole otherwise entails that the feedwater supplied will be automatically distributed to the individual tube banks according to the amount of heat supplied, so that local superheatings are avoided.

In all embodiments, the finished tube skeleton must, of course, be supposed to be covered externally with suitable covering plates and insulation 12.

I claim:

1. A tubulous boiler having riser tube side walls, a riser tube front wall, a riser tube rear wall, and a riser tube top wall forming in combination a radiant heat furnace, a drum located transversely in the rear part of the boiler for receiving steam and water mixture from the tubes of said riser tube Walls, downcomer tubes forming a vertical wall extending beneath and substantially the whole length of said drum and forming, together with said riser tube rear wall, at least one gas passage that extends substantially over the full width of the boiler, vaporizing tubes connected at one of their ends to the downcomer tubes of said vertical wall, and arranged in said passage to form a convection heating surface, means connecting the other ends of said vaporizing tubes to the drum, and a header at the lower end of said vertical wall connected to and receiving water from the downcomer tubes for distribution to the lower ends of said n'ser tube front and side walls.

2. A tubulous boiler as claimed in claim 1, in which the said convection heating surface consists at least substantially of inclined tubes emerging from the said downcomer tubes and merging into riser tubes.

3. A tubulous boiler as claimed in claim 2, in which some of said last mentioned riser tubes combine to form a partition parallel to the vertical downcomer tube wall and dividing said gas passage into a down-pass series-connected to an upward-pass.

4. A tubulous boiler as claimed in claim 1, in which each downcomer tube in said vertical downcomer tube wall together with its associated vaporizing tubes and connecting means constitute a substantially plane, separately fabricated tube grid.

5. A tubulous boiler as claimed in claim 1, in which a superheater is located in said gas passage on the up I stream side of the convection heating surface therein and shielded from the radiant furnace chamber by the riser tube rear wall thereof.

6. A tubulous boiler having riser tube side walls, a riser tube front wall, a riser tube rear wall and a riser tube top wall forming in combination a radiant heat furnace, a manifold located transversely in the rear part of the boiler for receiving water from the tubes of said riser tube walls, a vertical wall of tubes extending beneath and at least substantially the whole length of said manifold and forming, together with said riser tube rear wall at least one gas passage extending at least substantially over the full width of the boiler, a convection heating surface arranged in said passage and consisting of tubes connected at one end to the tubes of said vertical wall, means connecting the other ends of said tubes to the manifold, a header at the lower end of said vertical wall, and means for introducing water into said header for distribution to the lower ends of the tubes of all the tube walls.

7. A tubulous boiler having riser tube side walls, a riser tube front wall, a riser tube rear wall, and a riser tube top wall forming in combination a radiant heat furnace, collector means located transversely in the rear part of the boiler for receiving fluid discharged from the tubes of said riser tube walls, a vertical wall of tubes extending beneath and for substantially the whole length of said collector means and forming, together with said riser tube rear wall, at least one gas passage extending substantially over the full width of the boiler, a convection heating surface arranged in said passage and consisting of tubes connected at one end to the tubes of said vertical wall, means connecting the other ends of said tubes to said collector means, a header at the lower end of said vertical wall, and means connecting said header to the lower ends of said riser tube front and side walls.

References Cited in the file of this patent UNITED STATES PATENTS 2,741,228 Vorkauf Apr. 10, 1956 2,763,245 Place Sept. 18, 1956 FOREIGN PATENTS 152,328 Australia July 15, 1953 

